// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ui/base/cursor/cursor_util.h"

#include "base/logging.h"
#include "skia/ext/image_operations.h"
#include "ui/base/resource/resource_bundle.h"
#include "ui/gfx/geometry/point_conversions.h"
#include "ui/gfx/geometry/size_conversions.h"
#include "ui/gfx/image/image_skia.h"
#include "ui/gfx/skbitmap_operations.h"
#include "ui/gfx/skia_util.h"

namespace ui {

namespace {

    // Converts the SkBitmap to use a different alpha type. Returns true if bitmap
    // was modified, otherwise returns false.
    bool ConvertSkBitmapAlphaType(SkBitmap* bitmap, SkAlphaType alpha_type)
    {
        if (bitmap->info().alphaType() == alpha_type) {
            return false;
        }

        // Copy the bitmap into a temporary buffer. This will convert alpha type.
        SkImageInfo image_info = SkImageInfo::MakeN32(bitmap->width(), bitmap->height(), alpha_type);
        std::vector<char> buffer(bitmap->getSize());
        bitmap->readPixels(image_info, &buffer[0], image_info.minRowBytes(), 0, 0);
        // Read the temporary buffer back into the original bitmap.
        bitmap->reset();
        bitmap->allocPixels(image_info);
        memcpy(bitmap->getPixels(), &buffer[0], buffer.size());

        return true;
    }

} // namespace

void ScaleAndRotateCursorBitmapAndHotpoint(float scale,
    gfx::Display::Rotation rotation,
    SkBitmap* bitmap,
    gfx::Point* hotpoint)
{
    // SkBitmapOperations::Rotate() needs the bitmap to have premultiplied alpha,
    // so convert bitmap alpha type if we are going to rotate.
    bool was_converted = false;
    if (rotation != gfx::Display::ROTATE_0 && bitmap->info().alphaType() == kUnpremul_SkAlphaType) {
        ConvertSkBitmapAlphaType(bitmap, kPremul_SkAlphaType);
        was_converted = true;
    }

    switch (rotation) {
    case gfx::Display::ROTATE_0:
        break;
    case gfx::Display::ROTATE_90:
        hotpoint->SetPoint(bitmap->height() - hotpoint->y(), hotpoint->x());
        *bitmap = SkBitmapOperations::Rotate(
            *bitmap, SkBitmapOperations::ROTATION_90_CW);
        break;
    case gfx::Display::ROTATE_180:
        hotpoint->SetPoint(
            bitmap->width() - hotpoint->x(), bitmap->height() - hotpoint->y());
        *bitmap = SkBitmapOperations::Rotate(
            *bitmap, SkBitmapOperations::ROTATION_180_CW);
        break;
    case gfx::Display::ROTATE_270:
        hotpoint->SetPoint(hotpoint->y(), bitmap->width() - hotpoint->x());
        *bitmap = SkBitmapOperations::Rotate(
            *bitmap, SkBitmapOperations::ROTATION_270_CW);
        break;
    }

    if (was_converted) {
        ConvertSkBitmapAlphaType(bitmap, kUnpremul_SkAlphaType);
    }

    if (scale < FLT_EPSILON) {
        NOTREACHED() << "Scale must be larger than 0.";
        scale = 1.0f;
    }

    if (scale == 1.0f)
        return;

    gfx::Size scaled_size = gfx::ScaleToFlooredSize(
        gfx::Size(bitmap->width(), bitmap->height()), scale);

    *bitmap = skia::ImageOperations::Resize(
        *bitmap,
        skia::ImageOperations::RESIZE_BETTER,
        scaled_size.width(),
        scaled_size.height());
    *hotpoint = gfx::ScaleToFlooredPoint(*hotpoint, scale);
}

void GetImageCursorBitmap(int resource_id,
    float scale,
    gfx::Display::Rotation rotation,
    gfx::Point* hotspot,
    SkBitmap* bitmap)
{
    const gfx::ImageSkia* image = ResourceBundle::GetSharedInstance().GetImageSkiaNamed(resource_id);
    const gfx::ImageSkiaRep& image_rep = image->GetRepresentation(scale);
    // TODO(oshima): The cursor should use resource scale factor when
    // fractional scale factor is enabled. crbug.com/372212
    (*bitmap) = image_rep.sk_bitmap();
    ScaleAndRotateCursorBitmapAndHotpoint(
        scale / image_rep.scale(), rotation, bitmap, hotspot);
    // |image_rep| is owned by the resource bundle. So we do not need to free it.
}

void GetAnimatedCursorBitmaps(int resource_id,
    float scale,
    gfx::Display::Rotation rotation,
    gfx::Point* hotspot,
    std::vector<SkBitmap>* bitmaps)
{
    // TODO(oshima|tdanderson): Support rotation and fractional scale factor.
    const gfx::ImageSkia* image = ResourceBundle::GetSharedInstance().GetImageSkiaNamed(resource_id);
    const gfx::ImageSkiaRep& image_rep = image->GetRepresentation(scale);
    SkBitmap bitmap = image_rep.sk_bitmap();
    int frame_width = bitmap.height();
    int frame_height = frame_width;
    int total_width = bitmap.width();
    DCHECK_EQ(total_width % frame_width, 0);
    int frame_count = total_width / frame_width;
    DCHECK_GT(frame_count, 0);

    bitmaps->resize(frame_count);

    for (int frame = 0; frame < frame_count; ++frame) {
        int x_offset = frame_width * frame;
        DCHECK_LE(x_offset + frame_width, total_width);

        SkBitmap cropped = SkBitmapOperations::CreateTiledBitmap(
            bitmap, x_offset, 0, frame_width, frame_height);
        DCHECK_EQ(frame_width, cropped.width());
        DCHECK_EQ(frame_height, cropped.height());

        (*bitmaps)[frame] = cropped;
    }
}

} // namespace ui
